bulgaria-sofia: data services./ "printing, folding, enveloping and delivery of letters, messages and invoices to heat consumers." the subject of this contract is: "printing, folding, enveloping and delivery of letters, messages and invoices to heat consumers ”and includes the following activities: reception of personalized data, provided by the assignor electronically or through a technical medium with appropriate security measures of information; creation of standard forms for printing; data processing and control: sending to the assignor in pdf format, as well as in a format prepared by the contractor for entry into the electronic archive system of prepared individual invoices and messages to invoices; sending invoices to business customers and invoices and messages to invoices for household customers through a platform provided and managed by the contractor for sending digitally signed electronic documents by the assignor; production of materials for letters - standard forms; printing of personalized documents - invoices for household customers and messages to them and distribution of letters to mailboxes.